A digital processing system including a master chip having a first clock pin and a first data pin and a first slave chip having a second clock pin and a second data pin may be provided. The digital processing system may transmit first data from the master chip to the first slave chip based on a synchronous scheme in which a first clock signal output from the master chip via the first clock pin and the first data output from the master chip via the first data pin are provided together and the first data is transmitted in synchronization with the first clock signal, and may transmit second data from the first slave chip to the master chip based on an asynchronous scheme in which the second data output from the first slave chip via the second data pin is transmitted regardless of the first clock signal.